In the field of exposing an object to an electrical discharge, one known method is corona treatment. Corona treatment is the exposure of an object to a corona discharge, which is generated by exposing atmospheric air to different voltage potentials. A corona is the faint glow enveloping from an electrode in a corona discharge, often accompanied by streamers directed toward a second electrode. When a plastic substance is placed under the corona discharge, the electrons generated in the discharge impact on a surface of the substance to be treated with sufficient energy to break the molecular bonds on the treatment surface. Oxidation of the treatment surface increases the surface energy, allowing for better wetting by liquids and promoting adhesion. The oxidation results in an improved surface tension, which advantageously provides for improved bonding of liquids, adhesives, and inks to plastic surfaces and other surfaces.
One use for corona treatment is in treating the surfaces of plastic containers which contain household (and other) products, such as shampoo, cleaner, oil, paint, etc. One challenge in treating these containers is that the containers come in various shapes and sizes. Therefore, it would be advantageous to have a system for exposing a wide variety of extrusion or injection blow molded containers to an electrical discharge without requiring adjustment of the treatment system.
In one prior method of treating polyolefin objects, a conveyor belt provides an object to an electrical discharge apparatus for treatment. However, this system requires an alignment plate and an adjustable guiding arm. This system has the disadvantage of requiring operator adjustment to accommodate different treatment processes.
Also, many hollow objects, such as containers, are conveyed along a conveyor belt, which hollow objects will later be filled with a substance. Hollow objects leaving the corona system would preferably be in a filling position such that they may be more easily handled by a filling system that may be located further down a production line. For many hollow objects, this means that at least a relevant portion of an opening to the hollow object is substantially upright (i.e. within about 30° of being perpendicular to the conveyor).
Accordingly, what is needed is an improved system and method for exposing an object to an electrical discharge. Further, there is a need for such a system which does not require operator adjustments to accommodate various sizes and shapes of objects to be treated. Further still, what is needed is an improved guide having less rapid wear of the guide (due to the corona discharge between the guide and the electrode) and more optimal treatment of the object to be treated. Further still, what is needed is an improved wire electrode for optimal treatment of the object to be treated. Further still, what is needed is an improved system and method of providing the object at a predetermined distance from the electrode with better reliability than prior systems. Further still, what is needed is an improved system that can apply an electrical discharge to bottles which are upright.
The teachings hereinbelow extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned needs.